Companies have been urged to consult with staff before attempting marketing like the ill-fated Coles "I'm Free" campaign to avoid further risks of sexual harassment.

The union that represents retail staff including Coles employees said companies need to be more vigilant in their approach to protecting staff when using them in marketing campaigns.

Coles was forced to ditch its Easter advertising campaign after some employees waving an "I'm Free" paddle were sexually harassed by customers. The campaign was designed to help customers move through checkouts faster during the busy trading period. 

The promotional video showed a female Coles employee fanning herself with the "I'm Free" sign behind a tall man with muscles in a singlet top. 

Shop Distributors Association National Secretary Gerard Dwyer said employers were responsible for providing a safe working environment for staff.

"Companies need to be mindful of how their marketing and ad campaigns impact on staff," Mr Dwyer said.

"We like to see a system where staff are given the opportunity to provide input and feedback on marketing campaigns they will be responsible for implementing.

"Sexual harassment in any form is unacceptable."

Mr Dwyer said businesses that employ young workers should be "particularly sensitive and supportive in protecting them from customer abuse and sexual harassment".

In a post on The Age Facebook site, Alison Atkinson said: "The advertising agency and Coles created this problem. The ad finished with a flirtacious (sic) women (sic) trying to hit on a good looking customer. I'm in marketing and would never have let that happen! Phone me Coles."

Another reader, Libbi Curtis, posted that all she could think of when I first saw the ad "was Mr Humphries from Are You Being Served".

Joan Tolliday said: "And did Coles REALLY think that this wasn't going to happen???? Sounds more like clever marketing to me. And an the news this morning it was reported that most of the harassing was done by middle aged men....."

Sylvia Rapley said she took part in similar marketing when she was young. "I had to wear a badge for a shampoo product called "Free and Lovely" forgot to take it off and wore it on the train home".

The supermarket giant told Fairfax Media it had dumped the campaign after reports that customers had made inappropriate comments to staff. 

"Unfortunately in response to a small number of customers behaving disrespectfully to team members, we have now removed the hand-held signs," a Coles spokeswoman said.

The spokeswoman said Coles staff have loved being able to help shoppers get through the checkouts quicker during the busy Easter trading period.

"Use of the 'I'm Free' signs to indicate an open checkout was a fun way of activating the campaign," the spokeswoman said.

"Coles team members remain focused on delivering great service to our customers over the Easter period."

In the Easter advertising blitz Coles announced it was opening extra cashiers over the long weekend, but employees and their families have complained that the campaign has sexual undertones and puts staff at risk. 

Checkout staff who were encouraged to hold "I'm Free" signs as part of a new ad campaign said they had received unwanted advances from customers.

Coles employee Emily Henderson wrote on Facebook that she was horrified by comments customers had made in response to the signs.

"The comments have been horrible ... we have had it from BOTH (sic) male and female, old and young."

Cheryl Pole Hepburn wrote on Coles' Facebook page that she was "absolutely horrified" when she approached a cash register where staff were holding the signs on the weekend. 

"The verbal abuse and suggestions coming from customers to staff members was disgusting! I really think you need to rethink the whole idea – if I knew any friends daughters or sons applying for work as a cashier I'd advise against it!"

Another customer, Sonja Dada, shared a similar story: "In my local store ... I saw a register operator basically bullied in front of customers to stand with his sign by management ... I also heard of men catcalling objectifying (sic) young women working the registers. Take the signs away or lose customers to Woolies/Aldi's ... the response from service desk was appalling."

Kylie McKenzie wrote on Coles' Facebook page that she was relieved that the "dumb campaign signs" were taken off her daughters' cash register recently. 

"The number of lewd and suggestive comments made to the female service staff in the short time they had the signs in their hands, by mostly male customers including but not limited to, 'You're free? When can I take you home?' was absolutely disgusting," she said. 

"Some may argue that the customers were being cute or funny or conversational ... but think about grown men saying such things to your 16, 17 or 18 year old child, school aged child, whilst in her workplace. A place she should feel safe. And it wasn't only the young ones copping the comments."